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51.
Glauco F. Bauerfeldt Leila M. M. de Albuquerque Graciela Arbilla Edilson C. da Silva 《Journal of Molecular Structure》2002,580(1-3):147-160
The competitive unimolecular reactions of formaldehyde, H2CO→H2+CO; H2CO→trans-HCOH and H2CO→H+HCO, were comparatively studied under the direct dynamics formalism, using Density functional and ab initio levels of theory. In addition, the geometric isomerization trans-HCOH→cis-HCOH was evaluated. Calculated reaction path properties were used in the determination of Rice–Ramsperger–Kassel–Marcus microcanonical rate coefficients. The reaction dynamics was evaluated for each individual process based on the nuclear displacements in the reaction path and normal coordinate analysis. Our results found are in very good agreement with experimental barrier heights and quantum yields trends. 相似文献
52.
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54.
R. Albuquerque 《Expositiones Mathematicae》2019,37(2):207-224
We survey on the geometry of the tangent bundle of a Riemannian manifold, endowed with the classical metric established by S. Sasaki 60 years ago. Following the results of Sasaki, we try to write and deduce them by different means. Questions of vector fields, mainly those arising from the base, are related as invariants of the classical metric, contact and Hermitian structures. Attention is given to the natural notion of extension or complete lift of a vector field, from the base to the tangent manifold. Few results are original, but finally new equations of the mirror map are considered. 相似文献
55.
Dr. Joao Paulo Coelho Jonas Matern Dr. Rodrigo Q. Albuquerque Prof. Dr. Gustavo Fernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(38):8960-8964
Statistical copolymerization plays a key role in many biological and technological processes; however, mechanistic understanding of the formation of analogous supramolecular counterparts remains limited. Herein, we report detailed insights into the supramolecular co-assembly of two π-conjugated PdII and PtII complexes, which in isolation self-assemble into flexible fibers and nanodisks, respectively. An efficient single-step co-assembly into only one type of nanostructure (fibers or nanodisks) takes place if any of the components is in excess. In contrast, equimolar mixtures lead to PdII-rich fiber-like co-assemblies by a statistical co-nucleation event along with a residual amount of self-sorted nanodisks in a stepwise manner. 相似文献
56.
Adaildo Gomes d''Assunção Maria Rosa M. Lins de Albuquerque Everton N. R. Q. Fernandes 《International Journal of Infrared and Millimeter Waves》2000,21(12):2087-2097
We have studied the behavior of the microstrip lines on lossy biaxial anisotropic dielectric substrates. A spectral-domain moment method is used with the Galerkin testing procedure to determine the dispersion characteristics of single and coupled lines. Modes of both even and odd symmetries are included. It is found that the anisotropy of the substrate has a significant influence on the propagation characteristics. The theory is verified by comparison with previously published data. 相似文献
57.
Joo Albuquerque Susana Casal Rebeca Cruz Ingrid Van Dorpe Margarida Rosa Garcez Maia Antnio Jos Mira Fonseca Ana Rita Jordo Cabrita Ana Rute Neves Salette Reis 《Molecules (Basel, Switzerland)》2021,26(14)
Robust and selective quantification methods are required to better analyze feed supplementation effectiveness with specific amino acids. In this work, a reversed-phase high-performance liquid chromatography method with fluorescence detection is proposed and validated for lysine quantification, one of the most limiting amino acids in ruminant nutrition and essential towards milk production. To assess and widen method applicability, different matrices were considered: namely Li2CO3 buffer (the chosen standard reaction buffer), phosphate buffer solution (to mimic media in cellular studies), and rumen inoculum. The method was validated for all three matrices and found to be selective, accurate (92% ± 2%), and precise at both the inter- and intra-day levels in concentrations up to 225 µM, with detection and quantification limits lower than 1.24 and 4.14 µM, respectively. Sample stability was evaluated when stored at room temperature, 4 °C, and −20 °C, showing consistency for up to 48 h regardless of the matrix. Finally, the developed method was applied in the quantification of lysine on real samples. The results presented indicate that the proposed method can be applied towards free lysine quantification in ruminant feeding studies and potentially be of great benefit to dairy cow nutrition supplementation and optimization. 相似文献
58.
Rui Albuquerque 《Annali di Matematica Pura ed Applicata》2009,188(3):429-443
We consider some classical fibre bundles furnished with almost complex structures of twistor type, deduce their integrability
in some cases and study self-holomorphic sections of the general twistor space, with which we define a new moduli space of complex structures. We also recall the
theory of flag manifolds to study the Siegel domain and other domains alike, which are the fibres of various symplectic twistor
spaces. We prove that they are all Stein. In the context of a Riemann surface, with its canonical symplectic-metric connection
and local structure equations, the moduli space is studied again. 相似文献
59.
Heleno VC da Silva R Pedersoli S de Albuquerque S Bastos JK Silva ML Donate PM da Silva GV Lopes JL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(1):234-239
In this paper we present a complete 1H and 13C NMR spectral analysis of three lignan lactones (methylpluviatolide, dimethylmatairesinol and hinokinin) by the use of techniques such as COSY, HMQC, HMBC and J-resolved. Complete assignment and all homonuclear hydrogen coupling constant measurements were performed, providing enough data also to the confirmation of the relative stereochemistry. 相似文献
60.
Dias JM Lemos PC Serafim LS Oliveira C Eiroa M Albuquerque MG Ramos AM Oliveira R Reis MA 《Macromolecular bioscience》2006,6(11):885-906
Numerous bacteria have been found to exhibit the capacity for intracellular polyhydroxyalkanoates (PHA) accumulation. Current methods for PHA production at the industrial scale are based on their synthesis from microbial isolates in either their wild form or by recombinant strains. High production costs are associated with these methods; thus, attempts have been made to develop more cost-effective processes. Reducing the cost of the carbon substrates (e.g., through feeding renewable wastes) and increasing the efficiency of production technologies (including both fermentation and downstream extraction and recovery) are two such examples of these attempts. PHA production processes based on mixed microbial cultures are being investigated as a possible technology to decrease production costs, since no sterilization is required and bacteria can adapt quite well to the complex substrates that may be present in waste material. PHA accumulation by mixed cultures has been found under various operational conditions and configurations at both bench-scale and full-scale production. The process known as "feast and famine" or as "aerobic dynamic feeding" seems to have a high potential for PHA production by mixed cultures. Enriched cultures submitted to a transient carbon supply can synthesize PHA at levels comparable to those of pure cultures. Indeed, the intracellular PHA content can reach around 70% of the cell dry weight, suggesting that this process could be competitive with pure culture PHA production when fully developed. Basic and applied research of the PHA production process by mixed cultures has been carried out in the past decade, focusing on areas such as microbial characterization, process configuration, reactor operational strategies, process modeling and control, and polymer characterization. This paper presents a review of the PHA production process with mixed cultures, encompassing the findings reported in the literature as well as our own experimental results in relation to each of these areas. 相似文献